We have 5% and 6.5% acetic acid solutions and we need 200 ml of 6% acetic acid. Set up two equations: f means 5% and s means 6.5% A) f + s = 200 B) .05f + .065s = (.06 * 200) Multiplying equation A by -.05 A) -.05f -.05s = -10 B) .05f + .065s = 12 then adding both equations: .015s = 2 <span>
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we need 133.33</span> ml of 6.5% acetic acid and 66.67 ml of 5% acetic acid solution. </span> </span> Source: http://www.1728.org/mixture.htm